OBDI versus OBDII

[Chris VR6nos 0]

Can the OBDI system be changed to support the cheaper and seemingly better Film maf in place of the Hotwire maf?

 

In theory it should be possible as the late CP ecu uses the OBD2 MAF, but is still OBD1. I'm just wondering if VW recalibrated the CP ECU to run a film MAF as it's voltage outputs differ from the wire MAFs.

 

i'd like to go P8Pro and dump the maf all together but that as lots of other things, are a long way off at the moment for me!

 

 

Chris

[Dutch24V 0]

Why not just stick a CP ECU in and change the MAF to a film one? You can apparently disable the imob. with VAG-COM so wouldn't require the bits for that.

 

They can't cost much srom a scrappy and this would be easier surely?

...or am I missing something?

 

Dutch

[corradovr6sc 0]

Why not just stick a CP ECU in and change the MAF to a film one? You can apparently disable the imob. with VAG-COM so wouldn't require the bits for that.

 

They can't cost much srom a scrappy and this would be easier surely?

...or am I missing something?

 

Dutch

 

Something has to be done with the wiring though as the hotfilm maf uses fewer wires and has a different connector.

[Chris VR6nos 0]

Now that would be the conversion i'd be interested in, i know little about it ATM but there's got to be easier way to do it than the epicness of stepper motor throttle bodies etc etc.

I live and learn.

 

 

 

 

Chris

[Andi 2,147,483,647]

Isn't there someone from the Stealth Rolling Road meet just gone that is booking their VR into Stealth for a OBDI to II conversion?

 

Must be possible ;)

[Kevin Bacon 5]

Nice cut n paste Chris :-)

 

Regarding disabling the immobiliser via VAG-COM, that was what I was told when I got the parts for my conversion, but I later discovered it isn't possible after all. Unless the transponder setup is there, the ECU won't start the car at all. There's no way to circumvent it either, unless we can figure out what the pulses are that the tranny sends to the ECU and emulate them....but there again we hit a stumbling block because each ECU/tranny is uniquely coded....so you need the tranny in the first place in order to emulate it....so you may aswell just fit it, LOL!

 

Dumping the MAF would be a marvellous thing. If we can find a MAP sensor with a 1 to 5V output and fudge it so that the ECU thinks it's a MAF, it should work in theory.

 

Not sure what happened to Mike Edwards but I'm sure he ran an OBD2 MAF on an AG ECU but didn't go into the details.

 

I've got the wiring codes for both the wire and film MAFs, but you need an OBD2 plug. In theory you just need to lose the wire heater circuit from the OBD1 loom and it should work. As said before, the output at idle will be too low for an AG ECU. Not sure how you can get round that without a CP.

[Chris VR6nos 0]

it get's confusing but i want a late ECU like a CP one which runs OBDI software, this sounds the simplest route however i run a dizzy so need to suss out what i need to change, Wires likes making lists up so maybe he will for this when it's sussed. H8RRA has a cam end cover and a few spares he got given over time so could be a thing to try but might also need a cam change or will i?

 

 

 

Chris

[Kevin Bacon 5]

You just need Paul's end cover, a cam sensor + plug and loom, an impulse wheel on the rear cam, the pack of coilies and the coilie plug + loom and that there CP Emu.

 

Try finding a CP Emu though mate!!

 

What about that Megasquirt kit thingy? Quite cheap and good by all accounts. Won't need any form of Bosch Emu then...and you can use a MAP instead of a Mad Max MAF.

 

Tis all an ache of the balls.... do you need all this though? I thought yours was running OK? The wire just likes f'cking about with things and experimenting....I'd still be OK with OB1 kenobi but the OBD2 bits were offered, so.....

[corradovr6sc 0]

I think the switch to an obd1 hotfilm maf is well worth it if it can be done as they are cheaper (charged vrs do seem to have an appetite for mafs), less sensitive to turbulence and can be easily fitted into an oversize housing.

[Kevin Bacon 5]

Yep, £69 exchange for an OBD2 MAF, which is justification for the conversion in itself imo.

 

Chargers are hard on MAFs. On a standard engine, the MAF rarely sees enough air mass to give or exceed 5V, but with a charger, it shoots up to 5V frequently, they are very hard worked. A MAF a year is good going with chargers, but according to the American forums, some are on their 8th MAF over a couple of years but they pay peanuts for them compared to us.

 

Another thing you can do with the OBD2 MAF is fit a £40 MK4/Beetle 2.0 8V insert into the housing, so it really is cost effective.

 

As Chris recommends, I'd also vent the PCV gases to atmosphere instead of into the charger inlet. It's the water vapours and oil dripping that kills the MAFs quicker than air mass overloading.

 

On the turbulance, it's more the OBD2 cars that are less sensitive to turbulence because they don't rely on an ISV to maintain the idle. My MAF is just suspended vertically onto the charger inlet, it never stalls. And I also don't need to faff about with flexi ducting and tie wrapped MAFs 8)

[corradovr6sc 0]

Is the obd1 hotfilm maf identical (same part number) to the obd2 maf?

 

Yep, my crankcase gases are vented into the atmosphere (with a catchcan inbetween) but it still only lasts 18 months!

[Kevin Bacon 5]

Yep, I think they are. VW part number ends 461A or 462 but the bosch number you need is 0 280 217 512.

 

Same PCV setup as me then. 18 months is good going!

 

Were you pleased with your dyno results? I didn't get the oppurtunity for a chat..... 270hp is good for a stage 1 running OBD1!

[corradovr6sc 0]

The dyno results - first time on the rollers with the vortech using the z-engineering mapped chip. Happy with the power/torque (a bit less than I had with the Z-charger - 274hp/240lbft) but I had staggering transmission losses something I can't explain. Did you have high transmission losses? I had a loss of 40 hp before but this time it was 80! Feels ok powerwise on the road so I'm not sure why they were so high - any ideas?

[Kevin Bacon 5]

On Sunday my transmission loss was 49hp. Prior to a 4 wheel alignment at Stealth, I've seen a 60 hp loss, so it might be something to do with that, not sure. You might have had a bit of wheel spin, I've got a quaife so slip was minimal.

 

80 loss needs looking at really as that's way too high!

 

Interestingly, my on road performance doesn't feel like what the figures suggest but it's running stupidly rich at the moment.

[corradovr6sc 0]

I've had 4 wheel alignment done recently (with before and after figures) and it feels spot on on the road so I doubt its that. Maybe the heavier wheels and brakes have made a difference and the front tyre pressures were 32 psi which may be a bit low. Worth changing the gearbox oil for MT 90?

[Kevin Bacon 5]

Hmmm, but I'm running BBS 17s and 312s aswell..... and your RK2s are lighter than my RXs. I run my fronts at 32 psi aswell.

 

I have MT90 in my gbox, but I doubt that would account for such a low transmission loss compared to yours. I've also got a lower final drive and recent gbox rebuild, but again that doesn't really account for that 30hp wheel loss reduction. IIRC, there was another VR (standard) that had an 80hp loss too, which Vince put down to the geometry.

 

Dunno, it's a weird one for sure......I think it's probably more a problem with the rollers than your car personally.

[RW1 0]

Excuse for hitching back as I went for a cup of tea and things seemed to have wandered on..............

 

Tis all an ache of the balls.... do you need all this though?

 

Think that about sums it up. The dizzy & coil pack are very different beasts besides the MAF itself. Quite a few wires to change/not use/add. ECU drives the coil pack direct to add to the list although may not be relevant depending of conversion depth. For camshaft position sender read hall effect sender in the dizzy. Also, I've found the hot film MAF (OBD1) more sensitive to oily filters like K&N causing "chugging" and now run on a plain old VW filter which are changed out regularly at 10,000 miles. Admittedly the car is standard but it’s the same MAF at less airflow rates.

 

VAG-COM can't override the key immobiliser otherwise every thief would be equipped with it! Unless you get the matched immobiliser/keys with the donor "CP" ECU, you are at the mercy of the dealers to hook your motor to the VAS5051 and dial Southern Germany on the GEKO system. No code is visible to the garage and they can't do it by hand/fax/telephone anymore or refuse to point blank (issue with who owns the car under data protection at present and right to codes) as this was all stopped in 2002. (If you see Ebay ads for software to do this, its for second and third generation immobilisers, none of which were fitted with the Corrado "CP" ECU circuitry).

 

Bottom line as Kev says........ Not impossible but…… not a Sunday afternoon & dun though.

 

I'm still looking for a spare "CP" ECU after six years as only about 2,000 exist worldwide and it’s unique to the Corrado.

 

MAF…… 021 906 462 (Bosch 0 280 217 504) goes with the “CP” but I seem to remember someone on here buying in error a 021 906 462A (Bosch 0 280 217 512) MAF and saying the stock Corrado with “CP” ECU worked and was better (debatable as there was a MAF fault). 461’s are all hot wire MAFs I think???

 

.

[NickVR6 0]

Blimmey my head hurts after reading this puppy!

 

My trans losses were 71.3 bhp! Prob my cheap oreeblur wheels!

[Kevin Bacon 5]

Good info as ever Chris.

 

461 is wire, 461A and 462 are film MAFs IIRC, 462 is defo OBD2 film as that is what's on my car at the moment, 512 Bosch suffix as you say, so it's the same as CP MAFs and valid for the MK4/Beetle £40 insert :-)

[RW1 0]

Yeah, but the 462A is 512, on 1996 - 1997 Golfs etc., 462 is 504 on the Corrado, so 512 is not a CP related MAF but apparently works OK for someone on here. I can't remember but didn't your MAF come off a Golf '97. If so, I've just bought one off a G'97 and its a 462A.

 

461's have the alphabet of suffices and thats why I had ????.

 

.

[Dutch24V 0]

I could have swore when I replaced my MAF, the bosch dealers ordered the 461 and bosch sent the 462A as it's now supperceeded the 461?

 

I will try and dig out the receipt to confirm this...

 

Dutch

[H8RRA 0]

AAARRRGGGHHH!!!!!!!! We need a summary - i've totally lost the plot here!!!!!

 

As I have a CP ecu, my MAFS are reasonably cheap/same as obd2/can be replaced by beetle internals ? i need a standby spare and want to know what to keep an eye out for.

 

I'm still looking for a spare "CP" ECU after six years as only about 2,000 exist worldwide and it’s unique to the Corrado.

...but a replacement ecu is hard to find?????????

[Johnboy98 0]

Holy cr@p Batman, this is turning into one gaint turd pie and which ever slice you take you still get the nasty taste!

 

What would you say is the highest cause of early failure on Hot wire MAF's?

or is it a plethera of things!

[Kevin Bacon 5]

LOL! Tis all getting confusing now!

 

Not sure what the biggest cause of wire MAF failure is. Some last years, some last months. MAFs are well known across numerous manufacturers for being pants, god knows why they still use the silly things.

[Supercharged 2]

Holy cr@p Batman, this is turning into one gaint turd pie and which ever slice you take you still get the nasty taste!

 

:LOL: